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authorJakub Kicinski <kuba@kernel.org>2020-12-05 00:40:55 +0300
committerJakub Kicinski <kuba@kernel.org>2020-12-05 00:40:55 +0300
commit43be3a3c65ff9c0e4f2ac1c4a7e22784b3827695 (patch)
tree83b65a5607d34540f08b5e8a73a8342c4a0acef4 /drivers/nfc/s3fwrn5
parent4be986c824b8382119a0918ae3a138577a73cf9f (diff)
parent94ab9eb9b234ddf23af04a4bc7e8db68e67b8778 (diff)
downloadlinux-43be3a3c65ff9c0e4f2ac1c4a7e22784b3827695.tar.xz
Merge branch 'perf-optimizations-for-tcp-recv-zerocopy'
Arjun Roy says: ==================== Perf. optimizations for TCP Recv. Zerocopy This patchset contains several optimizations for TCP Recv. Zerocopy. Summarized: 1. It is possible that a read payload is not exactly page aligned - that there may exist "straggler" bytes that we cannot map into the caller's address space cleanly. For this, we allow the caller to provide as argument a "hybrid copy buffer", turning getsockopt(TCP_ZEROCOPY_RECEIVE) into a "hybrid" operation that allows the caller to avoid a subsequent recvmsg() call to read the stragglers. 2. Similarly, for "small" read payloads that are either below the size of a page, or small enough that remapping pages is not a performance win - we allow the user to short-circuit the remapping operations entirely and simply copy into the buffer provided. Some of the patches in the middle of this set are refactors to support this "short-circuiting" optimization. 3. We allow the user to provide a hint that performing a page zap operation (and the accompanying TLB shootdown) may not be necessary, for the provided region that the kernel will attempt to map pages into. This allows us to avoid this expensive operation while holding the socket lock, which provides a significant performance advantage. With all of these changes combined, "medium" sized receive traffic (multiple tens to few hundreds of KB) see significant efficiency gains when using TCP receive zerocopy instead of regular recvmsg(). For example, with RPC-style traffic with 32KB messages, there is a roughly 15% efficiency improvement when using zerocopy. Without these changes, there is a roughly 60-70% efficiency reduction with such messages when employing zerocopy. ==================== Link: https://lore.kernel.org/r/20201202225349.935284-1-arjunroy.kdev@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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